JP2006188676A - Polyester composition and polyester molded product composed of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester composition capable of efficiently producing a blow molded product excellent in transparency and having little variation of transparency, reduced in production of aldehydes such as acetaldehyde in molding, having adequate crystallization properties and excellent in heat resistance and dimensional stability and a polyester molded product composed of the polyester composition. <P>SOLUTION: The polyester composition comprises at least two kinds of polyesters having substantially same compositions and differing in intrinsic viscosity and a recovered material of polyester molded product as main components. In the polyester composition, the difference of intrinsic viscosity of polyesters is 0.05-0.30 deciliters/g and the content of the recovered material of the polyester molded article in the polyester composition is 0.1-10 wt.%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a hollow molded body including beverage bottles, a sheet-like article, a molded article such as a stretched film, and a coating coated on a substrate such as paper or film (hereinafter, these uses are referred to as “ A polyester composition suitably used as a raw material, such as a molded article, and a polyester molded article comprising the polyester composition, especially because of improved flow characteristics, excellent transparency and little variation in transparency, Formation of aldehydes such as acetaldehyde and their fluctuations are suppressed, and a hollow molded body with moderate crystallization characteristics and excellent heat-resistant dimensional stability and a sheet with excellent transparency, slipperiness and dimensional stability after molding And a stretched film.

  Polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”) are excellent in both mechanical properties and chemical properties, and thus have high industrial value, such as fibers, films, sheets, and bottles. Widely used as such.

  As a material for containers such as seasonings, oils, beverages, cosmetics, and detergents, various resins are employed depending on the type of filling contents and the purpose of use.

  Of these, polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier properties, and is particularly suitable as a material for molded articles such as beverage filling containers such as juices, soft drinks and carbonated drinks. is there.

  For example, such polyester is supplied to a molding machine such as an injection molding machine to form a preform for a hollow molded body, and the preform is inserted into a mold having a predetermined shape and stretched blow molded to cool it. It is made into a hollow molded container for beverages, or it is molded into a heat-resistant or pressure-resistant hollow molded container by heat-treating the preform plug part (crystallization of the plug part) and then stretching blow molding and heat-treating the body part (heat set). It is common. However, when the crystallization of the plug portion is insufficient or the variation in crystallinity is large, the sealing performance with the cap is deteriorated, and the contents may leak.

  In order to solve such problems, in the case of beverages that require hot filling, such as fruit juice beverages, oolong tea, and mineral water, the mouth portion of the preform or molded bottle is heat-treated and crystallized. A method (for example, see Patent Document 1) is common. Such a method, that is, a method of improving the heat resistance by heat-treating the plug portion and the shoulder portion, the time and temperature for the crystallization treatment greatly affect the productivity, and can be processed at a low temperature in a short time. It is preferable that the conversion rate is PET. On the other hand, the body portion is required to be transparent even if heat treatment is performed at the time of molding so as not to deteriorate the color tone of the contents of the bottle, and the mouthpiece portion and the body portion must have contradictory characteristics.

  In the case of PET, in order to solve such a problem of mold contamination, conventionally, a method of reducing the cyclic trimer, which is the main component of the deposit on the mold surface, by solid-phase polymerization in advance (for example, In this method, the cyclic trimer is regenerated when it is remelted and preformed, and its effect is insufficient. Also disclosed are a method of deactivating a catalyst by contact treatment with water (for example, see Patent Document 2) and a PET having a catalyst deactivated by water treatment (for example, see Patent Document 3). Yes. However, even with the above method, the amount of cyclic oligomer produced at the time of melting is reduced and the mold contamination is reduced temporarily. However, the crystallization speed is unstable, the plug portion dimension accuracy is poor, and the shape is whitened. There are problems that defects such as flow patterns and bubbles are likely to occur, and only bottles with poor transparency can be obtained, and there is a need for a solution.

  PET contains acetaldehyde (hereinafter sometimes abbreviated as AA) as a by-product during melt polycondensation. Moreover, PET produced acetaldehyde by thermal decomposition when thermoforming a molded body such as a hollow molded body, and the acetaldehyde content in the material of the obtained molded body was increased, and the hollow molded body was filled. Affects the flavor and odor of beverages. In recent years, polyester containers such as polyethylene terephthalate have come to be used as containers for low flavor beverages such as mineral water and oolong tea. In the case of such beverages, these beverages are generally heat-filled or sterilized by heating after filling, but it is becoming increasingly important to reduce the acetaldehyde content of the beverage container. In addition, for beverage metal cans, for the purposes of process simplification, hygiene, pollution prevention, etc., cans are made using a metal plate whose inner surface is coated with a polyester film containing ethylene terephthalate as the main repeating unit. The method to do has come to be adopted. In this case as well, the contents are filled and sterilized by heating at a high temperature. At this time, it is found that the use of a film having a sufficiently low acetaldehyde content is an essential requirement for improving the flavor and odor of the contents. I came.

For these reasons, various measures have been taken to reduce the acetaldehyde content in the polyester. As these measures, for example, a method of reducing the AA content by solid-phase polymerization of melt-polycondensed polyester (see, for example, Patent Document 4), AA at the time of molding using a copolyester having a lower melting point A method of reducing the production (for example, see Patent Document 5), a method of using a polyester composition in which 0.05 parts by weight or more and less than 1 part by weight of a metaxylylene group-containing polyamide resin is added to 100 parts by weight of the polyester resin (for example, Patent Document 6), a method for reducing the molding temperature as much as possible during thermoforming, a method for reducing the shear stress as much as possible during thermoforming, and the like have been proposed. However, even in a molded body using polyester obtained by these methods, it cannot be said that oligomers and acetaldehyde can be reduced to a problem-free level, and the problem remains unsolved. In addition, a blend of solid-phase polymerized PET and copolymerized polyethylene terephthalate (for example, see Patent Document 7) has been proposed. By using this, the AA content of the hollow molded body can be reduced. Since the copolymer component is present, there is a problem in the heat resistance and pressure resistance of the obtained molded body, which is not satisfactory and a solution is awaited.
In recent years, thinning of bottles has been attempted, and as a result, attempts have been made to increase the molecular weight in order to increase the strength of the bottle, but by increasing the molecular weight, the melt viscosity during molding increases and the amount of acetaldehyde generated increases. There was an increasing problem.

  Various proposals have been made to solve the problems of improvement and stabilization of the crystallization rate. For example, there is a method of adding an inorganic nucleating agent such as kaolin and talc to polyethylene terephthalate (see, for example, Patent Document 8), but these methods are problematic in practical use with the generation of foreign matter and cloudiness.

  Further, a method of adding a treated polyester obtained by pulverizing a polyester molded body obtained by melt molding from the polyester to the raw material polyester (see, for example, Patent Documents 9 and 10), hydrolyzing the polyester and the intrinsic viscosity A particle mixture (for example, Patent Document 11) with polyester reduced by 0.01 to 0.25 dl / g has been proposed. However, these measures require capital investment for the melt molding and pulverization process and the hydrolysis process at 100 ° C or higher, and the quality of the polyester obtained by melt molding is not stable. It is very difficult to obtain a polyester which has a stable crystallization speed and gives a molded article having excellent dimensional stability and transparency of the plug after heat crystallization, which is preferable economically and in quality. It is not a policy.

  Moreover, the manufacturing method of the container using the composition which consists of two types of polyester which has the crystallization temperature at the time of temperature rising and crystallization temperature at the time of temperature fall of a specific range and which has intrinsic viscosity of a different range (for example, refer patent document 12) However, it is difficult to produce bottles with excellent transparency and heat resistance by high-speed molding, and there is a problem in recyclability, such as adversely affecting transparency when re-molding used containers.

  In addition, a PET modification method by bringing a PET chip into contact with a polyethylene member under flow conditions, a polyester resin composition in which 0.1 to 45 ppb of polyethylene is blended with a polyester resin (for example, see Patent Document 13), etc. Although proposed, such a method and a polyester resin composition have an appropriate and stable crystallization speed, are free from defects such as whitened flow patterns and bubbles, and have excellent transparency. It has been found that it is very difficult to obtain a molded article having excellent heat-resistant dimensional stability.

  That is, depending on the prior art, a polyester composition that has an appropriate crystallization speed and efficiently gives a polyester molded body having a reduced acetaldehyde content by high-speed molding has not yet been obtained, and a solution is awaited.

JP 55-89330 A Japanese Patent Laid-Open No. 3-47830 Japanese Patent Laid-Open No. 3-72524 JP-A-53-73288 Japanese Patent Laid-Open No. 57-16024 Japanese Examined Patent Publication No. 6-6661 JP 58-45254 A JP 56-2342 A Japanese Patent Laid-Open No. 5-105807 JP-A-6-116392 JP-A-6-116485 Japanese Patent Laid-Open No. 10-287799 JP-A-9-151308

  The present invention solves the above-mentioned problems of the prior art, is a hollow molded body, a sheet-like product that is excellent in transparency and has little variation in transparency, and that suppresses the generation of aldehydes such as acetaldehyde during molding, Efficient high-speed molding of molded articles such as stretched films and polyester compositions that are suitable for use as materials such as coatings on substrates, and hollow molded articles with moderate crystallization characteristics and excellent heat-resistant dimensional stability It is an object of the present invention to provide a polyester composition that can be produced and a polyester molded body comprising the same. Furthermore, it aims at the reuse of the collect | recovered goods of a polyester molded object.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to achieve the above object. That is, the polyester composition of the present invention is a polyester composition comprising, as main components, at least two types of polyesters having substantially the same composition but having different intrinsic viscosities, and a recovered product of the polyester molded product. The difference in intrinsic viscosity of the polyester is in the range of 0.05 to 0.30 deciliter / gram, and the content of the recovered polyester molded product in the polyester composition is 0.1 to 10% by weight. It is a polyester composition characterized by these.
Here, “substantially the same” means that the acid component and the glycol component in each polyester are 95 mol% or more, more preferably 97 mol% or more, particularly 98 mol% or more. It is preferable.

  The difference in intrinsic viscosity of the polyester constituting the polyester composition of the present invention is preferably 0.06 to 0.27 deciliter / gram, more preferably 0.07 to 0.23 deciliter / gram, and particularly preferably 0.10. ~ 0.20 deciliter / gram. When the intrinsic viscosity difference is less than 0.05 deciliter / gram, the transparency of the molded product obtained by molding at a low temperature of 290 ° C. or lower is deteriorated, and on the other hand, the transparency of the molded product is improved. Under molding temperature conditions, the content of aldehydes such as acetaldehyde cannot be reduced, and flavor retention cannot be improved. On the other hand, when the above intrinsic viscosity difference exceeds 0.30 deciliter / gram, thickness irregularities, whitened flow patterns, and the like occur in the obtained molded product, resulting in a problem of poor transparency. Here, when the polyester composition of the present invention comprises two or more kinds of polyesters, the difference in intrinsic viscosity is the difference in intrinsic viscosity between the maximum polyester and the minimum polyester with respect to the intrinsic viscosity.

  The recovered polyester molded body that constitutes the polyester composition of the present invention can be obtained by heating the polyester with a melt molding machine such as an injection molding machine to form a molded body or a sheet-like product and then not shipping it as a product. It is a polyester molded body that is collected and mixed again with the virgin raw material polyester for use in molding, and may be referred to as a “collected product” hereinafter. Specifically, the recovered product is a product, an intermediate product such as a preform, a product that does not satisfy the product standard, a burr such as a runner generated during molding, and the like. These recovered products need to be cut or pulverized to have a size of about 1 to 10 mm, and a size substantially comparable to the size of the virgin raw material is preferable.

The content of the recovered product of the polyester molded body in the polyester composition is 0.1 to 10% by weight.
The content of the recovered product is preferably 0.5 to 5% by weight. If the content of the recovered product exceeds 10% by weight, the effect of promoting crystallization becomes too great and the transparency of the preform becomes poor, or the crystallization of the hollow molded body plug part becomes excessive, Since the amount of shrinkage of the plug part does not fall within the specified value range, the capping part of the plug part becomes defective and the contents may leak. When the content of the recovered product is less than 0.1% by weight, the crystallization speed becomes very slow, and the crystallization of the plug part of the hollow molded body becomes insufficient. In some cases, the amount of shrinkage does not reach the specified value range, resulting in capping failure.
The inclusion of the recovered product is also desirable from the viewpoint of reusing the recovered product of the polyester molded body.

  That is, the polyester composition of the present invention is a polyester composition that can be molded at a lower temperature because the fluidity at the time of melting in the extruder is improved by the action of the lower intrinsic viscosity polyester, It is possible to reduce the content of aldehydes such as acetaldehyde, improve the transparency, and optimize the crystallization speed of the obtained molded product. At the same time, the orientation during heating and stretching is also improved, so it is possible to give stretched molded articles with excellent mechanical properties such as elastic modulus and tensile strength, and also excellent heat fixability, and particularly excellent heat resistance. It can be beneficially used as a stretched hollow container.

  In this case, the recovered polyester molded product is a polyester mixture containing at least two polyesters as main components, having substantially the same composition and a difference in intrinsic viscosity of 0.05 to 0.30 deciliter / gram. It is obtained by melt molding, and it is preferable that the composition of the polyester of the recovered product is substantially the same as the composition of the polyester according to claim 1.

In this case, it is preferable that the dispersion ratio Mz / Mn of the molecular weight distribution of the recovered polyester molded product is 3.80 or more.
In this case, it is preferable that the aldehyde content of the recovered polyester molded product is 20 ppm or less.

In this case, the cyclic ester oligomer content of the recovered polyester molded product is preferably 70% or less of the cyclic ester oligomer content of the melt polycondensed polyester.
In this case, it is preferable that the increase amount of the cyclic ester oligomer when the recovered polyester molded product is melted at a temperature of 290 ° C. for 60 minutes is 0.40% by weight or less.

In this case, the above polyester can be molded.
In this case, the polyester molded body is a hollow molded body preform, a sheet-shaped preform, or a stretched film or stretch blow hollow molded body obtained by stretching these preforms in at least one direction. Can be any chosen.
Moreover, in this case, it can be a coating obtained by melt-extruding the polyester composition on a substrate.

  The polyester composition of the present invention has a low content of aldehydes such as acetaldehyde, is excellent in flavor retention and transparency, has a low cyclic ester oligomer content, has an appropriate crystallization speed, and is a mold during continuous molding. It is possible to give a molded body with little occurrence of dirt, such as a hollow molded body, a sheet-like product, a stretched film, or a coating on a substrate.

  Since the flow characteristics are improved, the present invention is excellent in transparency and has little variation in transparency, the amount of aldehyde generated during molding and its variation is small, and an appropriate crystallization rate when formed into a molded body And a polyester composition that gives a molded article having excellent mechanical properties. In addition, the polyester composition of the present invention has improved flow characteristics, so there is less distortion during molding, and a molded body with an appropriate heat-resistant dimensional stability with a moderate crystallization speed, especially a hollow molded product, can be efficiently obtained by high-speed molding. Provided is a polyester molded body that can be produced well and has excellent long-term continuous moldability with less staining of the mold. The polyester composition of the present invention can meet high quality requirements in the field of containers, sheets and the like.

Hereinafter, embodiments of the polyester composition of the present invention will be specifically described.
The polyester according to the present invention is a thermoplastic polyester mainly obtained from an aromatic dicarboxylic acid component and a glycol component, preferably a polyester containing 70 mol% or more of an aromatic dicarboxylic acid unit of the acid component, more preferably A polyester containing 85 mol% or more of an aromatic dicarboxylic acid unit, particularly preferably a polyester containing 95 mol% or more of an aromatic dicarboxylic acid unit of an acid component.

  The aromatic dicarboxylic acid component constituting the polyester according to the present invention includes aromatic dicarboxylic acids such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and the like. And functional derivatives.

  Examples of the glycol component constituting the polyester according to the present invention include aliphatic glycols such as ethylene glycol, 1,3-trimethylene glycol and tetramethylene glycol, and alicyclic glycols such as cyclohexanedimethanol.

  Examples of the dicarboxylic acid used as a copolymerization component when the polyester is a copolymer include isophthalic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and 4,4′-diphenyl ether dicarboxylic acid. , Aromatic dicarboxylic acids such as 4,4′-diphenyl ketone dicarboxylic acid and functional derivatives thereof, oxyacids such as p-oxybenzoic acid and oxycaproic acid and functional derivatives thereof, adipic acid, sebacic acid, succinic acid, Examples thereof include aliphatic dicarboxylic acids such as glutaric acid and dimer acid and functional derivatives thereof, and alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid and cyclohexanedicarboxylic acid, and functional derivatives thereof.

  The glycol as a copolymerization component used when the polyester is a copolymer is diethylene glycol, 1,3-trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene. Glycols, 2-ethyl-2-butyl-1,3-propanediol, aliphatic glycols such as neopentyl glycol, dimer glycol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol 1,4-cyclohexane dimethylol, 2,5-norbornane dimethylol and other alicyclic glycols, xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4′-β-hydroxyethoxy) Aromatic glycols such as phenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, and alkylene oxide adducts of bisphenol A, polyalkylene glycols such as polyethylene glycol and polybutylene glycol Etc.

  Furthermore, examples of the polyfunctional compound as a copolymer component used when the polyester is a copolymer include trimellitic acid, pyromellitic acid, and the like as an acid component, and glycerin and pentane as glycol components. Mention may be made of erythritol. The amount of copolymerization component used should be such that the polyester remains substantially linear. Monofunctional compounds such as benzoic acid and naphthoic acid may be copolymerized.

  A preferred example of the polyester according to the present invention is a polyester whose main structural unit is composed of ethylene terephthalate, more preferably 70 mol% or more of ethylene terephthalate units, and isophthalic acid, 1,4-cyclohexanedi, as a copolymerization component. A copolyester containing methanol or the like, particularly preferably a polyester containing 95 mol% or more of ethylene terephthalate units.

  Examples of these polyesters include polyethylene terephthalate (hereinafter abbreviated as PET), poly (ethylene terephthalate-ethylene isophthalate) copolymer, poly (ethylene terephthalate-1,4-cyclohexanedimethylene terephthalate) copolymer, poly ( Examples thereof include an ethylene terephthalate-dioxyethylene terephthalate) copolymer, a poly (ethylene terephthalate-1,3-propylene terephthalate) copolymer, and a poly (ethylene terephthalate-ethylene cyclohexylene dicarboxylate) copolymer.

In addition, another preferable example of the polyester according to the present invention is a polyester in which the main structural unit is composed of 1,3-propylene terephthalate, and more preferably a polyester including 70 mol% or more of 1,3-propylene terephthalate units. Particularly preferred are polyesters containing 95 mol% or more of 1,3-propylene terephthalate units.
Examples of these polyesters include polypropylene terephthalate (PTT), poly (1,3-propylene terephthalate-1,3-propylene isophthalate) copolymer, poly (1,3-propylene terephthalate-1,4-cyclohexanedimethylene). Terephthalate) copolymer and the like.

  Furthermore, other preferable examples of the polyester according to the present invention are polyesters in which the main structural unit is composed of butylene terephthalate, more preferably a copolyester containing 70 mol% or more of butylene terephthalate units, and particularly preferable. Is a polyester containing 95 mol% or more of butylene terephthalate units.

  Examples of these polyesters include polybutylene terephthalate (PBT), poly (butylene terephthalate-butylene isophthalate) copolymer, poly (butylene terephthalate-1,4-cyclohexanedimethylene terephthalate) copolymer, poly (butylene terephthalate- 1,3-propylene terephthalate) copolymer, poly (butylene terephthalate-butylene cyclohexylene dicarboxylate) copolymer, and the like.

  Another preferred example of the polyester according to the present invention is a thermoplastic polyester in which the main structural unit is composed of ethylene-2,6-naphthalate, and more preferably 70 mol% or more of ethylene-2,6-naphthalate unit. The thermoplastic polyester is particularly preferably a thermoplastic polyester containing 90 mol% or more of ethylene-2,6-naphthalate units.

  Examples of these thermoplastic polyesters include polyethylene-2,6-naphthalate (PEN), poly (ethylene-2,6-naphthalate-ethylene terephthalate) copolymer, poly (ethylene-2,6-naphthalate-ethylene isophthalate). ) Copolymer, poly (ethylene-2,6-naphthalate-dioxyethylene-2,6-naphthalate) copolymer, and the like.

  Further, another preferred example of the polyester according to the present invention is a polyester in which the main structural unit is composed of 1,4-cyclohexanedimethylene terephthalate, and more preferably 70 mol% or more of 1,4-cyclohexanedimethylene terephthalate units. And a polyester containing 90 mol% or more of 1,4-cyclohexanedimethylene terephthalate units.

  Examples of these thermoplastic polyesters include poly-1,4-cyclohexanedimethylene terephthalate (PCT), poly (1,4-cyclohexanedimethylene terephthalate-ethylene terephthalate) copolymer, and the like.

  The polyester according to the present invention can basically be produced by a conventionally known melt polycondensation method or melt polycondensation method-solid phase polymerization method. The melt polycondensation reaction may be performed in one stage or may be performed in multiple stages. These may be comprised from a batch-type reaction apparatus, and may be comprised from the continuous-type reaction apparatus. The melt polycondensation step and the solid phase polymerization step may be operated continuously or may be operated separately. Hereinafter, an example of a preferable continuous production method of the polyester according to the present invention will be described by taking polyethylene terephthalate (PET) as an example, but the present invention is not limited thereto. That is, a direct esterification method in which terephthalic acid, ethylene glycol, and if necessary, other copolymerization components are directly reacted and esterified while distilling off water, followed by polycondensation under reduced pressure in the presence of a polycondensation catalyst, Or transesterification by reacting dimethyl terephthalate with ethylene glycol and other copolymerization components if necessary, and transesterifying while distilling off methyl alcohol, followed by polycondensation under reduced pressure in the presence of a polycondensation catalyst Manufactured by. Then, when the intrinsic viscosity is increased or the low acetaldehyde content or the low cyclic trimer content is used, such as a heat-resistant container for low flavor beverages or a film for inner surfaces of metal cans for beverages. The resulting melt polycondensed polyester is subsequently subjected to solid state polymerization.

  First, when a low polymer is produced by an esterification reaction, 1.02 to 2.0 mol, preferably 1.03 to 1.4 mol of ethylene glycol is added to 1 mol of terephthalic acid or an ester derivative thereof. The contained slurry is prepared and continuously supplied to the esterification reaction step.

In the esterification reaction, water or alcohol produced by the reaction is removed out of the system by a rectification column under conditions where ethylene glycol is refluxed using a multistage apparatus in which at least two esterification reactors are connected in series. While implementing. The temperature of the first stage esterification reaction is 240 to 270 ° C., preferably 245 to 265 ° C., and the pressure is 0.2 to 3 kg / cm ² G, preferably 0.5 to ² kg / cm ² G. The temperature of the esterification reaction in the final stage is usually 250 to 280 ° C, preferably 255 to 275 ° C, and the pressure is usually 0 to 1.5 kg / cm ² G, preferably 0 to 1.3 kg / cm ² G. . When carried out in three or more stages, the reaction conditions for the esterification reaction in the intermediate stage are conditions between the reaction conditions for the first stage and the reaction conditions for the final stage. The increase in the reaction rate of these esterification reactions is preferably distributed smoothly at each stage. Ultimately, it is desirable that the esterification reaction rate reaches 90% or more, preferably 93% or more. By these esterification reactions, low-order condensates having a molecular weight of about 500 to 5,000 are obtained.

  When terephthalic acid is used as a raw material, the esterification reaction can be carried out without a catalyst by the catalytic action of terephthalic acid as an acid, but may be carried out in the presence of a polycondensation catalyst.

  Also, tertiary amines such as triethylamine, tri-n-butylamine, benzyldimethylamine, quaternary ammonium hydroxides such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, trimethylbenzylammonium hydroxide, and lithium carbonate When a small amount of a basic compound such as sodium carbonate, potassium carbonate or sodium acetate is added, the proportion of dioxyethylene terephthalate component units in the main chain of polyethylene terephthalate is relatively low (5% relative to all diol components). Mol% or less).

  Next, in the case of producing a low polymer by transesterification, 1.1 to 2.0 mol, preferably 1.2 to 1.5 mol of ethylene glycol was contained with respect to 1 mol of dimethyl terephthalate. The solution is prepared and continuously fed to the transesterification step.

  The transesterification reaction is carried out while removing methanol generated by the reaction outside the system using a rectification column under the condition that ethylene glycol is distilled back using an apparatus in which 1 to 2 transesterification reactors are connected in series. To do. The temperature of the first stage transesterification is 180 to 250 ° C, preferably 200 to 240 ° C. The temperature of the transesterification reaction in the final stage is usually 230 to 270 ° C., preferably 240 to 265 ° C., and as the transesterification catalyst, fatty acid salts such as Zn, Cd, Mg, Mn, Co, Ca, Ba, carbonates Alternatively, Pb, Zn, Sb, Ge oxide or the like is used. A low-order condensate having a molecular weight of about 200 to 500 is obtained by these transesterification reactions.

  Dimethyl terephthalate, terephthalic acid or ethylene glycol, which is the starting material, includes virgin dimethyl terephthalate derived from para-xylene, ethylene glycol derived from terephthalic acid or ethylene, as well as methanol decomposition from used PET bottles. A recovered raw material such as dimethyl terephthalate, terephthalic acid, bishydroxyethyl terephthalate or ethylene glycol recovered by a chemical recycling method such as decomposition of ethylene glycol or ethylene glycol can also be used as at least part of the starting material. Needless to say, the quality of the recovered raw material must be refined to a purity and quality suitable for the intended use.

  Subsequently, the obtained low-order condensate is supplied to a multistage liquid phase condensation polymerization process. The polycondensation reaction conditions are as follows: the first stage polycondensation reaction temperature is 250 to 290 ° C., preferably 260 to 280 ° C., and the pressure is 500 to 20 Torr, preferably 200 to 30 Torr. The temperature is 265 to 300 ° C., preferably 275 to 295 ° C., and the pressure is 10 to 0.1 Torr, preferably 5 to 0.5 Torr. When carried out in three or more stages, the reaction conditions for the intermediate stage polycondensation reaction are conditions between the reaction conditions for the first stage and the reaction conditions for the last stage. The degree of increase in intrinsic viscosity achieved in each of these polycondensation reaction steps is preferably distributed smoothly. A single-stage polycondensation apparatus may be used for the polycondensation reaction.

  The polycondensation reaction is performed using a polycondensation catalyst. As the polycondensation catalyst, at least one compound selected from Ge, Sb, Ti, or Al compounds is preferably used. These compounds are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries and the like.

  Examples of the Ge compound include amorphous germanium dioxide, crystalline germanium dioxide powder or ethylene glycol slurry, a solution obtained by heating and dissolving crystalline germanium dioxide in water, or a solution obtained by adding ethylene glycol to this and heat treatment. In particular, in order to obtain the polyester used in the present invention, it is preferable to use a solution in which germanium dioxide is dissolved by heating in water, or a solution in which ethylene glycol is added and heated. In addition, compounds such as germanium tetroxide, germanium hydroxide, germanium oxalate, germanium chloride, germanium tetraethoxide, germanium tetra-n-butoxide, and germanium phosphite can also be used. These polycondensation catalysts can be added during the esterification step. When a Ge compound is used, the amount used is preferably 10 to 150 ppm, more preferably 13 to 100 ppm, still more preferably 13 to 50 ppm, and most preferably 15 to 45 ppm as the residual amount of Ge in the polyester.

  Examples of Ti compounds include tetraalkyl titanates such as tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate, tetra-n-butyl titanate, and partial hydrolysates thereof, titanium acetate, titanyl oxalate, titanyl oxalate, titanyl oxalate Sodium, titanyl oxalate, titanyl calcium oxalate, titanyl oxalate compounds such as titanium strontium oxalate, titanium trimellitate, titanium sulfate, titanium chloride, titanium halide hydrolyzate, titanium oxalate, titanium fluoride, titanium hexafluoride Titanium with potassium acid, ammonium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, titanium acetylacetonate, hydroxy polyvalent carboxylic acid or nitrogen-containing polyvalent carboxylic acid A phosphorus compound is reacted with a complex compound, a composite oxide composed of titanium and silicon or zirconium, a reaction product of titanium alkoxide and a phosphorus compound, or a reaction product of titanium alkoxide and an aromatic polycarboxylic acid or its anhydride. The reaction product obtained by the above. The Ti compound is added so that the amount of Ti remaining in the produced polymer is 0.1 to 50 ppm, preferably 0.5 to 10 ppm.

  Examples of the Sb compound include antimony trioxide, antimony acetate, antimony tartrate, antimony potassium tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, and triphenylantimony. The Sb compound is added so that the residual amount of Sb in the produced polymer is in the range of 50 to 300 ppm, preferably 50 to 250 ppm, preferably 50 to 200 ppm, and more preferably 50 to 180 ppm.

  Al compounds include aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum carbonate, aluminum phosphate, aluminum phosphonate and other inorganic acid salts, aluminum n-propoxide, aluminum iso-propoxide Aluminum alkoxides such as aluminum n-butoxide and aluminum t-butoxide, aluminum chelate compounds such as aluminum acetylacetonate, aluminum acetylacetate, aluminum ethylacetoacetate, aluminum ethylacetoacetate diiso-propoxide, trimethylaluminum, triethylaluminum, etc. Organic aluminum compounds and partial hydrolysates thereof, aluminum oxide, etc. It is. Of these, aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride and aluminum acetylacetonate are particularly preferred. The Al compound is added so that the Al remaining amount in the produced polymer is in the range of 5 to 200 ppm, preferably 10 to 50 ppm.

  In the production of polyester A and polyester B according to the present invention, an alkali metal compound or an alkaline earth metal compound may be used in combination as necessary. The alkali metal or alkaline earth metal is preferably at least one selected from Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba, and the use of an alkali metal or a compound thereof is more preferable. preferable. When using an alkali metal or a compound thereof, use of Li, Na, K is particularly preferable. Examples of the alkali metal and alkaline earth metal compounds include saturated aliphatic carboxylates such as formic acid, acetic acid, propionic acid, butyric acid, and succinic acid, and unsaturated aliphatic carboxylates such as acrylic acid and methacrylic acid. , Aromatic carboxylates such as benzoic acid, halogen-containing carboxylates such as trichloroacetic acid, hydroxycarboxylates such as lactic acid, citric acid and salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, phosphorus Inorganic acid salts such as acid hydrogen, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid, hydrobromic acid, chloric acid and bromic acid, and organic sulfonates such as 1-propanesulfonic acid, 1-pentanesulfonic acid and naphthalenesulfonic acid , Organic sulfates such as lauryl sulfate, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert-butyl Alkoxides such as alkoxy, chelate compounds and the like acetylacetonate, hydrides, oxides, and hydroxides and the like.

  The alkali metal compound or alkaline earth metal compound is added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution, or the like. The alkali metal compound or alkaline earth metal compound is added so that the residual amount of these elements in the produced polymer is in the range of 1 to 50 ppm.

  Furthermore, polyester A and polyester B according to the present invention were selected from the group consisting of silicon, manganese, iron, cobalt, zinc, gallium, strontium, zirconium, niobium, molybdenum, indium, tin, hafnium, thallium, tungsten. A metal compound containing at least one element may be contained. These metal compounds include saturated aliphatic carboxylates such as acetates of these elements, unsaturated aliphatic carboxylates such as acrylates, aromatic carboxylates such as benzoic acid, and halogens such as trichloroacetic acid. Hydroxycarboxylates such as carboxylates and lactates, inorganic acid salts such as carbonates, organic sulfonates such as 1-propanesulfonate, organic sulfates such as lauryl sulfate, oxides, hydroxides, chlorides Products, alkoxides, acetylacetonates, and the like, and are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries, and the like. These metal compounds are added so that the residual amount of elements of these metal compounds per 1 ton of produced polymer is in the range of 0.05 to 3.0 mol. These metal compounds can be added at any stage of the polyester formation reaction step.

  Also, as stabilizers, phosphoric acid, phosphoric acid esters such as polyphosphoric acid and trimethyl phosphate, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, phosphine compounds It is preferable to use at least one phosphorus compound selected from the group consisting of: Specific examples include phosphoric acid, phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid tributyl ester, phosphoric acid triphenyl ester, phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid monobutyl ester, phosphoric acid dibutyl ester, Phosphoric acid, phosphorous acid trimethyl ester, phosphorous acid triethyl ester, phosphorous acid tributyl ester, methylphosphonic acid, methylphosphonic acid dimethyl ester, ethylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenylphosphonic acid Diphenyl ester and the like. These stabilizers can be added during the esterification reaction step from a slurry preparation tank of terephthalic acid and ethylene glycol. The P compound is added so that the residual amount of P in the produced polymer is preferably in the range of 5 to 100 ppm.

  When an Al compound is used as the polycondensation catalyst, it is preferably used in combination with a phosphorus compound, and is preferably used as a solution or slurry in which an aluminum compound and a phosphorus compound are previously mixed in a solvent. In the case of an Al compound, a more preferable phosphorus compound is at least one selected from the group consisting of phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, and phosphine compounds. It is a phosphorus compound. By using these phosphorus compounds, an effect of improving the catalytic activity is seen, and an effect of improving physical properties such as thermal stability of the polyester is seen. Among these, use of a phosphonic acid compound is preferable because of its great effect of improving physical properties and improving catalytic activity. Among the above-described phosphorus compounds, the use of a compound having an aromatic ring structure is preferable because the physical property improving effect and the catalytic activity improving effect are great.

  The melt polycondensation polyester obtained as described above is, for example, a method in which the melt polyester is extruded into water from the die pores after completion of the melt polycondensation and cut in water, or after the melt polycondensation is finished in the air from the die pores. After being extruded into strands, the chips are formed into columns, spheres, squares or plates by a method of forming chips while cooling with cooling water.

Moreover, as the cooling water at the time of chip formation of the melt polycondensed polyester, it is preferable to use cooling water satisfying at least one of the following (1) to (4), and more preferably (1) to (4 It is most preferable to use water that satisfies all of the above.
Na ≦ 1.0 (ppm) (1)
Mg ≦ 1.0 (ppm) (2)
Si ≦ 2.0 (ppm) (3)
Ca ≦ 1.0 (ppm) (4)

  The sodium content (Na) in the cooling water is preferably Na ≦ 0.5 ppm, more preferably Na ≦ 0.1 ppm. The magnesium content (Mg) in the cooling water is preferably Mg ≦ 0.5 ppm, more preferably Mg ≦ 0.1 ppm. Further, the content (Si) of silicon in the cooling water is preferably Si ≦ 0.5 ppm, more preferably Si ≦ 0.3 ppm. Furthermore, the calcium content (Ca) in the cooling water is preferably Ca ≦ 0.5 ppm, and more preferably Ca ≦ 0.1 ppm.

  In order to reduce sodium, magnesium, calcium, and silicon in the cooling water, an apparatus for removing sodium, magnesium, calcium, and silicon is installed in at least one place until the industrial water is sent to the chip cooling process. Also, a filter is installed to remove clay minerals such as silicon dioxide and aluminosilicate particles. Examples of the device for removing sodium, magnesium, calcium, and silicon include an ion exchange device, an ultrafiltration device, and a reverse osmosis membrane device.

  Next, the previous melt polycondensed polyester chip is preferably pre-crystallized in a continuous crystallization apparatus having two or more stages in an inert gas atmosphere. For example, in the case of PET, the temperature of 100 to 180 ° C. is 1 minute to 5 hours in the first stage precrystallization, and then the temperature of 160 to 210 ° C. is 1 minute to 3 hours in the second stage precrystallization. In the pre-crystallization of the second and higher stages, it is preferable to perform crystallization step by step at a temperature of 180 to 210 ° C. for 1 minute to 3 hours. The crystallinity of the chip after crystallization is preferably in the range of 30 to 65%, preferably 35 to 63%, and more preferably 40 to 60%. The crystallinity can be obtained from the density of the chip.

  Next, solid phase polymerization is carried out in an inert gas atmosphere or under reduced pressure at an optimum temperature for the prepolymer so that the increase in intrinsic viscosity due to solid phase polymerization is 0.10 deciliter / gram or more. For example, in the case of PET, the upper limit of the solid phase polymerization temperature is preferably 215 ° C. or lower, more preferably 210 ° C. or lower, particularly 208 ° C. or lower, and the lower limit is 190 ° C. or higher, preferably 195 ° C. or higher. is there.

  It is preferable to set the chip temperature to about 70 ° C. or less, preferably 60 ° C. or less, more preferably 50 ° C. or less within about 30 minutes, preferably within 20 minutes, more preferably within 10 minutes after completion of the solid phase polymerization.

  The shape of the polyester chip according to the present invention may be any of a cylinder shape, a square shape, a spherical shape, a flat plate shape, and the like. The average particle diameter is usually 1.0 to 4 mm, preferably 1.0 to 3.5 mm, and more preferably 1.0 to 3.0 mm. For example, in the case of a cylinder type, it is practical that the length is about 1.0 to 4 mm and the diameter is about 1.0 to 4 mm. In the case of spherical particles, it is practical that the maximum particle size is 1.1 to 2.0 times the average particle size and the minimum particle size is 0.7 times or more the average particle size. The weight of the chip is practically in the range of 2 to 50 mg / piece.

  When the polyester according to the present invention is a polyester having ethylene terephthalate as a main repeating unit, the polyester mixture constituting the polyester composition of the present invention contains the following polyester A and polyester B as main components, A polyester mixture in which the difference between the crystallization temperature when A cools and the crystallization temperature when polyester B cools is within 20 ° C. is preferable.

Polyester A: A polyester having an intrinsic viscosity IV _A of 0.60 to 0.80 deciliter / gram, an acetaldehyde content of 10 ppm or less, and a crystallization temperature measured by DSC of 160 to 200 ° C.
Polyester B: Polyester having an intrinsic viscosity IV _B of 0.73 to 0.95 deciliter / gram, an acetaldehyde content of 10 ppm or less, and a crystallization temperature measured by DSC of 160 to 200 ° C.

  The difference between the crystallization temperature when the temperature of the polyester A is lowered and the crystallization temperature when the temperature of the polyester B is lowered is preferably within 18 ° C, more preferably within 15 ° C, and particularly preferably within 10 ° C. When the difference in the crystallization temperature when the temperature is lowered exceeds 20 ° C., the transparency of the obtained molded product is very poor. In addition, the lower limit of the difference in crystallization temperature when the temperature is lowered is 2 ° C. or more, and if it is less than this, the difference in effect is not clear. Here, when the polyester mixture according to the present invention is composed of two or more kinds of polyesters, the difference in the crystallization temperature at the time of temperature decrease is the value of the polyester having the highest temperature crystallization temperature and the value of the lowest temperature crystallization. Represents the difference in the value of polyester with temperature.

The intrinsic viscosity IV _A of polyester A is preferably 0.62 to 0.75 deciliter / gram, more preferably 0.65 to 0.73 deciliter / gram, and the acetaldehyde content is preferably 8 ppm or less, more preferably 5 ppm or less. The crystallization temperature at the time of temperature reduction is preferably 162 to 190 ° C, more preferably 165 to 180 ° C. If the intrinsic viscosity IV _A of the polyester A is less than 0.60 dl / g is a problem deteriorates the transparency of the resulting molded product. On the other hand, if it exceeds 0.80 deciliter / gram, the effect of reducing acetaldehyde is lowered. On the other hand, when the acetaldehyde content exceeds 10 ppm, the flavor retention of the obtained molded product is deteriorated, which is problematic, but on the other hand, in the economically profitable method, 1 ppm is the limit. When the crystallization temperature at the time of temperature reduction of the polyester A is less than 160 ° C., the crystallization speed is slow when the unstretched portion of the polyester molded product is crystallized, and the productivity of the molded product becomes worse. Moreover, when it exceeds 200 degreeC, the transparency of a polyester molded object worsens and it is a problem.

The intrinsic viscosity IV _B of polyester B is preferably 0.74 to 0.90 deciliter / gram, more preferably 0.75 to 0.85 deciliter / gram, and the acetaldehyde content is preferably 8 ppm or less, more preferably 5 ppm or less. The crystallization temperature at the time of temperature reduction is preferably 162 to 190 ° C, more preferably 165 to 180 ° C. The intrinsic viscosity of the polyester B IV _B If there is less than 0.73 dl / g is a problem deteriorates the transparency of the resulting molded product. On the other hand, if it exceeds 0.95 deciliter / gram, heat generation during molding becomes intense and the effect of reducing acetaldehyde becomes low. On the other hand, when the acetaldehyde content exceeds 10 ppm, the flavor retention of the obtained molded product is deteriorated, which is problematic, but on the other hand, in the economically profitable method, 1 ppm is the limit. When the crystallization temperature at the time of temperature reduction of the polyester A is less than 160 ° C., the crystallization speed is slow when the unstretched portion of the polyester molded product is crystallized, and the productivity of the molded product becomes worse. Moreover, when it exceeds 200 degreeC, the transparency of a polyester molded object worsens and it is a problem.

  By using the polyester composition of the present invention, the content of aldehydes such as acetaldehyde is less, the color tone, flavor retention and transparency are excellent, and there is no occurrence of transparency spots, and an appropriate crystallization rate is achieved. Thus, it is possible to obtain a stretched molded article having excellent heat fixability with less fluctuation in crystallization speed. In particular, in the case of a thick stretched molded product such as a bottle, these effects become significant.

  When the polyester according to the present invention is a polyester having ethylene terephthalate as the main repeating unit, the polyester mixture constituting the polyester composition of the present invention contains the following polyester C and polyester D as main components. The polyester mixture is preferably a polyester mixture in which the difference between the crystallization temperature when the temperature of the polyester C is lowered and the crystallization temperature when the temperature of the polyester D is lowered is within 20 ° C.

Polyester C: Polyester having an intrinsic viscosity IV _C of 0.60 to 0.80 deciliter / gram, a crystallization temperature when heated by 140 to 180 ° C. and a crystallization temperature of 160 to 200 ° C. as measured by DSC .
Polyester D: Polyester having intrinsic viscosity IV _D of 0.73 to 0.95 deciliter / gram, crystallization temperature measured by DSC at 140 to 180 ° C., and crystallization temperature at 150 to 200 ° C. .
Here, the DSC measurement is performed by the following method on a molded plate (2 mm thickness) injection-molded at 290 ° C. by the following method.

  As polyester C or polyester D, it is possible to use at least one kind of each polyester that falls within the above characteristic range. For example, as polyester C, two kinds of polyesters that differ only in IV are used, and as polyester D, one kind is used. It is also possible to use a polyester mixed with the above-described composition ratio using the above polyester.

  The difference between the crystallization temperature when the temperature of the polyester C is lowered and the crystallization temperature when the temperature of the polyester D is lowered is as described above.

The intrinsic viscosity IV _C of polyester C is preferably 0.62 to 0.78 deciliter / gram, more preferably 0.63 to 0.75 deciliter / gram, and the crystallization temperature at the time of temperature rise is preferably 145 to 178 ° C. More preferably, it is 150-175 degreeC, and the crystallization temperature at the time of temperature reduction becomes like this. Preferably it is 162-190 degreeC, More preferably, it is 165-180 degreeC. If the intrinsic viscosity IV _C of the polyester C is less than 0.60 dl / g is a problem deteriorates the transparency of the resulting molded product. On the other hand, if it exceeds 0.80 deciliter / gram, the effect of reducing acetaldehyde is lowered. Moreover, when the crystallization temperature at the time of raising the temperature of polyester C is less than 140 ° C., the transparency of the molded article is deteriorated, and when it exceeds 180 ° C., the effect of improving the crystallization rate of the plug portion is deteriorated. When the crystallization temperature at the time of temperature reduction of the polyester C is less than 160 ° C., the effect of improving the crystallization speed of the plug portion is deteriorated, and when it exceeds 200 ° C., the transparency of the molded article is deteriorated.

The intrinsic viscosity IV _D of polyester D is preferably 0.74 to 0.90 deciliter / gram, more preferably 0.75 to 0.85 deciliter / gram, and the crystallization temperature at the time of temperature rise is preferably 150 to 178 ° C. More preferably, it is 155 to 175 ° C., and the crystallization temperature at the time of temperature reduction is preferably 155 to 190 ° C., more preferably 160 to 180 ° C. If the intrinsic viscosity IV _D of the polyester D is less than 0.73 dl / g is a problem deteriorates the transparency of the resulting molded product. On the other hand, if it exceeds 0.95 deciliter / gram, heat generation during molding becomes intense and the effect of reducing acetaldehyde becomes low. Moreover, when the crystallization temperature at the time of raising the temperature of the polyester D is less than 140 ° C., the transparency of the molded article is deteriorated. When the crystallization temperature at the time of temperature reduction of polyester D is less than 150 ° C., the effect of improving the crystallization speed of the plug portion is deteriorated, and when it exceeds 200 ° C., the transparency of the molded article is deteriorated.

  By using the polyester composition of the present invention having the above characteristics, the fluidity in the melt molding machine is further improved, so that molding at a lower temperature is possible, and the content of aldehydes such as acetaldehyde is further reduced. Excellent in flavor retention and transparency, and free from the occurrence of the above-mentioned transparency spots (for example, whitened flow pattern or partially whitened or wrinkled product formed on the molded product) A polyester molded body such as an excellent stretched polyester hollow molded body can be obtained. In particular, these effects become remarkable in the case of a thick stretched molded body such as a bottle.

  When the polyester according to the present invention is a polyester whose main repeating unit is ethylene-2,6-naphthalate (hereinafter sometimes abbreviated as PEN), the intrinsic viscosity of at least two kinds of polyesters is 0. It is selected from polyesters in the range of 40 to 0.80 deciliter / gram, preferably 0.42 to 0.75 deciliter / gram, more preferably 0.45 to 0.70 deciliter / gram. When the IV is less than 0.40 deciliter / gram, the mechanical properties of the obtained molded article are poor. In addition, when it exceeds 0.80 deciliter / gram, it becomes necessary to increase the resin temperature at the time of melting by a molding machine or the like, and this is accompanied by thermal decomposition, increasing the number of aldehydes such as acetaldehyde, and the molded product becomes yellow. Problems such as coloring occur.

  Furthermore, when the polyester according to the present invention is PEN, it contains the following polyester E and polyester F as main components, and the difference between the crystallization temperature of polyester E when it cools and the crystallization temperature of polyester F when it falls Is preferably a polyester mixture having a temperature within 20 ° C.

Polyester E: Polyester having an intrinsic viscosity IV _E of 0.40 to 0.70 deciliter / gram, a crystallization temperature when heated by 180 to 235 ° C. measured by DSC, and a crystallization temperature of 160 to 210 ° C. when lowered. .
Polyester F: Polyester having an intrinsic viscosity IV _F of 0.50 to 0.80 deciliter / gram, a crystallization temperature at the time of temperature rise of 180 to 235 ° C. measured by DSC, and a crystallization temperature at the time of temperature drop of 160 to 210 ° C. .

  When the polyester according to the present invention is a polyester whose main structural unit is 1,3-propylene terephthalate, the intrinsic viscosity of at least two polyesters is 0.50 to 1.00 deciliter / gram. Selected from polyesters in the range of 0.55 to 0.90 deciliter / gram, more preferably 0.60 to 0.85 deciliter / gram. When the intrinsic viscosity is less than 0.50 deciliter / gram, the mechanical properties of the obtained molded article are deteriorated, which is a problem. The upper limit of the intrinsic viscosity is 1.00 deciliter / gram. If the upper limit is exceeded, the resin temperature at the time of molding becomes high, the thermal decomposition becomes severe, the molecular weight decreases drastically, and the generation of aldehydes is intense. In addition, problems such as yellowing occur.

  The polyester according to the present invention can be produced by appropriately controlling the type and amount of polycondensation catalyst, melt polycondensation, solid phase polymerization conditions, and the like. It can also be obtained by a method of giving an impact to the polyester chip thus obtained, and a method of blending a polyolefin resin, particularly polyethylene, polyamide resin, polyoxymethylene resin, etc. as described below.

Further, the recovered product of the polyester molded body according to the present invention comprises at least two kinds of polyesters having substantially the same composition, and the difference in intrinsic viscosity is preferably 0.06 to 0.27 deciliter / gram, more preferably. Is preferably obtained by melt molding a polyester mixture containing as a main component a polyester of 0.07 to 0.23 deciliter / gram, particularly preferably 0.10 to 0.20 deciliter / gram. When the difference in intrinsic viscosity of the polyester constituting the recovered polyester material is less than 0.05 deciliter / gram, the content of aldehydes in the recovered product increases, which is not preferable. On the other hand, when it exceeds 0.30 deciliter / gram, there is a problem in that the effect of reducing aldehydes is lost or the transparency of the obtained polyester molding is deteriorated.
Further, the intrinsic viscosity of the recovered product is 0.60 to 0.85 deciliter / gram, preferably 0.63 to 0.80 deciliter / gram in the case of PET. If it is less than 0.60 deciliter / gram, the mechanical properties of the obtained polyester molded article are deteriorated, and if it exceeds 0.85 deciliter / gram, the transparency is adversely affected.

  In addition, the composition of the recovered polyester is preferably substantially the same as the composition of the virgin polyester used. Here, substantially the same composition means that the acid component and the glycol component in each polyester are preferably 95 mol% or more, more preferably 97 mol% or more, particularly 98 mol% or more. Preferably there is.

  Further, the dispersion ratio Mz / Mn of the molecular weight distribution of the recovered polyester molded product is preferably 3.85 or more, more preferably 3.90 or more, and particularly preferably 4.00 or more. When a recovered product having a molecular weight distribution dispersion ratio Mz / Mn of less than 3.80 is used, the resulting polyester molded article has poor transparency, and the molding temperature must be increased to ensure transparency. Therefore, aldehydes such as acetaldehyde cannot be reduced.

  As a method for obtaining a recovered product having a molecular weight distribution dispersion ratio Mz / Mn of 3.80 or more, for example, a polyester composition obtained by blending two or more polyesters having substantially the same composition but different molecular weights is molded under specific molding conditions. Method, a method of molding a polyester composition copolymerized with a polyfunctional compound under specific molding conditions, conditions during polycondensation (for example, in the case of a continuous polycondensation device, the residence time is increased, the number of polycondensation tanks, etc. For example, a method of molding a polyester having a dispersion ratio Mz / Mn of 3.80 or more obtained by appropriately adjusting the adjustment), and particularly a polyester composition in which two or more polymers having different molecular weights are blended. A method of molding as follows is preferred. That is, it is necessary to adjust the molten resin temperature, residence time, shear rate, screw configuration, etc. as conditions during the heat-melting treatment. Specifically, the temperature, residence time, and shear rate should not be increased more than necessary within the range that can be uniformly kneaded, and the screw configuration will ensure plug flow, so do not insert more mixing screws or reverse screws. In addition, it is possible to shorten the melt residence time as much as possible.

  The content of dialkylene glycol copolymerized in the polyester according to the present invention is preferably 0.5 to 7.0 mol%, more preferably 1.0 to 6% of the glycol component constituting the polyester. It is 0.0 mol%, More preferably, it is 1.0-5.0 mol%. When the amount of dialkylene glycol exceeds 7.0 mol%, the thermal stability is deteriorated, the decrease in molecular weight becomes large during molding, and the increase in the content of aldehydes is unfavorable. Further, in order to produce a polyester having a dialkylene glycol content of less than 0.5 mol%, it is necessary to select uneconomical production conditions as transesterification conditions, esterification conditions or polymerization conditions. Do not fit. Here, the dialkylene glycol copolymerized in the polyester, for example, in the case of a polyester whose main structural unit is ethylene terephthalate, is a diethylene glycol by-produced during production from ethylene glycol, which is a glycol. Among them, diethylene glycol (hereinafter abbreviated as DEG) copolymerized with the polyester, and glycol in the case of a polyester resin having 1,3-propylene terephthalate as a main constituent unit. Among di (1,3-propylene glycol) (or bis (3-hydroxypropyl) ether) by-produced from 1,3-propylene glycol during production, di (1,3-propylene) copolymerized with the polyester is used. Propylene glycol (hereinafter referred to as DPG).

  And the amount of diethylene glycol copolymerized in the polyester according to the present invention, particularly the polyester in which the main repeating unit is composed of ethylene terephthalate is 1.0 to 5.0 mol% of the glycol component constituting the polyester, Preferably it is 1.3-4.5 mol%, More preferably, it is 1.5-4.0 mol%. When the amount of diethylene glycol exceeds 5.0 mol%, the thermal stability is deteriorated, the decrease in molecular weight becomes large at the time of molding, and the increase in the acetaldehyde content and the formaldehyde content becomes large. On the other hand, when the diethylene glycol content is less than 1.0 mol%, the transparency of the obtained molded article is deteriorated.

  In addition, the content of aldehydes such as acetaldehyde in the polyester according to the present invention is 50 ppm or less, preferably 30 ppm or less, more preferably 10 ppm or less. When the aldehyde content exceeds 50 ppm, the effect of flavor retention of contents such as a molded article formed from a polyester composition containing such a polyester as a constituent component is deteriorated. Further, these lower limits are preferably 0.1 ppb from the viewpoint of production. Here, the aldehydes are acetaldehyde when the polyester is a polyester having ethylene terephthalate as a main constituent unit, and allylaldehyde in the case of a polyester having 1,3-propylene terephthalate as a main constituent unit. It is. In particular, when the polyester composition of the present invention is composed of a polyester having ethylene terephthalate as a main repeating unit, and this is used as a material for containers for low flavor beverages such as mineral water, The acetaldehyde content of is desirably 10 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, and most preferably 4 ppm or less.

  Further, the content of the cyclic ester oligomer of the polyester according to the present invention is 70% or less, preferably 60% or less, more preferably 50% of the content of the cyclic ester oligomer contained in the melt polycondensation polyester prepolymer of the polyester. Hereinafter, it is particularly preferably 35% or less. Here, the polyester generally contains cyclic ester oligomers having various degrees of polymerization, but the cyclic ester oligomer referred to in the present invention is the cyclic ester oligomer having the largest content among the cyclic ester oligomers contained in the polyester. An ester oligomer means, for example, a cyclic trimer in the case of a polyester having ethylene terephthalate as a main repeating unit.

  In the case of PET, in which the polyester is a representative polyester having ethylene terephthalate as a main constituent unit, the content of the cyclic trimer of the melt polycondensed polyester prepolymer is about 1.0% by weight, and therefore the present invention is concerned. The content of the polyester cyclic trimer is 0.70% by weight or less, preferably 0.60% by weight or less, more preferably 0.50% by weight or less, and particularly preferably 0.35% by weight or less. preferable. The lower limit of the cyclic trimer content is 0.28% by weight or more, preferably 0.29% by weight or more, and more preferably 0.30% by weight or more from the viewpoint of economical production. When molding a heat-resistant hollow molded article or the like from the polyester composition of the present invention, heat treatment is carried out in a heating mold, and the content of the cyclic trimer of each polyester is 0.70% by weight or more. In this case, the adhesion of the oligomer to the surface of the heating mold is rapidly increased, and the transparency of the obtained hollow molded body is extremely deteriorated.

  The content of aldehydes such as acetaldehyde in the recovered polyester molded product is 20 ppm or less, preferably 18 ppm or less, more preferably 15 ppm or less. When the aldehyde content exceeds 20 ppm, the effect of maintaining the flavor of the contents such as a molded article is deteriorated. In order to reduce the content of aldehydes in the recovered product to 20 ppm or less, a method using a solid-phase polymer as a raw material polyester of the recovered product, a method of appropriately selecting molding conditions when molding the recovered product, and dispersion of molecular weight distribution Examples thereof include a method using a polyester having a ratio Mz / Mn of greater than 3.80 and a method of appropriately combining them.

  Further, the content of the cyclic ester oligomer in the recovered product of the polyester molded product according to the present invention is 70% or less, preferably 60% or less, of the content of the cyclic ester oligomer contained in the polyester melt polycondensation polyester prepolymer. More preferably, it is 50% or less, and particularly preferably 40% or less. In the case of PET, which is a representative polyester having ethylene terephthalate as the main structural unit, the content of the cyclic trimer of the recovered product of the polyester molded product according to the present invention is 0.70% by weight or less, preferably It is preferably 0.60% by weight or less, more preferably 0.50% by weight or less, particularly preferably 0.40% by weight or less. The lower limit of the cyclic trimer content is 0.30% by weight or more, preferably 0.33% by weight or more from the viewpoint of economical production. When molding a heat-resistant hollow molded article or the like from the polyester composition of the present invention, heat treatment is performed in a heating mold, but the content of the cyclic trimer of the recovered product is 0.70% by weight or more. In this case, the adhesion of the oligomer to the surface of the heating mold is rapidly increased, and the transparency of the obtained hollow molded article is extremely deteriorated. In order to reduce the content of the cyclic ester oligomer in the recovered product to 70% or less of the content of the cyclic ester oligomer contained in the melt polycondensate of the polyester, the recovered polyester material is melt polycondensed, and then the solid phase Obtained by polymerization.

Further, the increase amount of the cyclic ester oligomer when the recovered polyester molded product is melted at a temperature of 290 ° C. for 60 minutes is preferably 0.3% by weight or less, more preferably 0.20% by weight or less, most preferably 0.1% by weight or less.
When the polyester resin of the present invention is a polyester having ethylene terephthalate as a main repeating unit, as described above, the cyclic ester oligomer is a cyclic trimer, so that the cyclic trimer when melted at a temperature of 290 ° C. for 60 minutes. The amount of increase in body is preferably 0.40% by weight or less.
The recovered product in which the increase amount of the cyclic ester oligomer when melted at a temperature of 290 ° C. for 60 minutes is 0.40% by weight or less is the weight of at least one polyester constituting the polyester mixture used for obtaining the recovered product. It can be produced by deactivating the condensation catalyst.

  Examples of the method of deactivating the polyester polycondensation catalyst include a method of contacting the polyester chip with water, water vapor or water vapor-containing gas.

Examples of the hot water treatment method include a method of immersing polyester in water and a method of applying water on these chips with a shower. The treatment time is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the water temperature is 20 to 180 ° C., preferably 40 to 150 ° C., more preferably 50 to 120 ° C. The water to be used is preferably water that satisfies at least one of the above (1) to (4), and more preferably water that satisfies all of (1) to (4).

  When the polyester chip and water vapor or water vapor containing gas are brought into contact with each other, the water vapor or water vapor containing gas or water vapor containing air at a temperature of 50 to 150 ° C., preferably 50 to 110 ° C., is preferably 1 kg of granular polyester. The water vapor is supplied in an amount of 0.5 g or more as water vapor, or is present to bring the granular polyester into contact with water vapor. The contact between the polyester chip and water vapor is usually performed for 10 minutes to 2 days, preferably 20 minutes to 10 hours. The processing method may be either a continuous method or a batch method.

  Further, as another means for deactivating the polycondensation catalyst, there is a method in which a phosphorus compound is blended with the polyester and mixed and reacted in a molten state such as during molding to deactivate the polycondensation catalyst.

  As a method of blending a phosphorous compound with polyester, a predetermined amount of phosphorous compound is polyester by a method of dry blending the phosphorous compound with the polyester or a method of mixing a polyester masterbatch chip in which a phosphorous compound is melt-kneaded and blended with a polyester chip. And a method of inactivating the polycondensation catalyst by melting in an extruder or a molding machine, a method of immersing chips in a phosphorus compound solution, particularly a phosphoric acid aqueous solution, and a method of adding as a master batch. These phosphorus compounds may be copolymerized with polyester.

  Examples of the phosphorus compound used include phosphoric acid, phosphorous acid, phosphonic acid, and derivatives thereof. Specific examples thereof are the compounds described above, and these may be used alone or in combination of two or more.

  In addition, the polyester according to the present invention is preferably deactivated in the same manner as the raw material polyester of the recovered product.

  Furthermore, it is preferable that the polyester composition of the present invention contains 0.1 ppb to 50000 ppm of at least one resin selected from the group consisting of polyolefin resins, polyamide resins, and polyacetal resins. The blending ratio of the resin used in the present invention to the polyester is 0.1 ppb to 10000 ppm, preferably 0.3 ppb to 1000 ppm, more preferably 0.5 ppb to 100 ppm, still more preferably 1.0 ppb to 1 ppm, particularly preferably. 1.0 ppb to 45 ppb. When the blending amount is less than 0.1 ppb, the crystallization speed becomes very slow and the crystallization of the plug part of the hollow molded body becomes insufficient. Therefore, if the cycle time is shortened, the shrinkage amount of the plug part is specified. Since it does not fall within the value range, it becomes a problem of capping failure. On the other hand, if it exceeds 50000 ppm, the crystallization speed becomes high, and the crystallization of the plug portion of the hollow molded body becomes excessive, and the shrinkage amount of the plug portion does not fall within the specified value range, resulting in capping failure and the content. Leakage, and the preform for the hollow molded body is whitened, which makes normal stretching impossible. Further, in the case of a sheet-like material, if it exceeds 50000 ppm, the transparency becomes very poor, the stretchability is also impaired, and normal stretching is impossible, and only a stretched film with large thickness spots and poor transparency can be obtained. .

Further, the polyester composition of the present invention includes polyamide, polyesteramide, low molecular weight amino group-containing compound, hydroxyl group-containing compound, hindered phenyl compound, hindered amine compound, benzotriazole compound, benzophenone as an aldehyde reducing agent. Compound, polyphenol compound, phosphorus stabilizer, sulfur stabilizer, alkali metal salt can be blended, preferably polyamide, benzophenone compound, polyesteramide, phosphorus stabilizer, low molecular weight amino group-containing compound , A hydroxyl group-containing compound, a benzophenone compound, a hindered phenyl compound, and a hindered amine compound can be blended. Most preferably, it is a polyamide, a polyesteramide, or a low molecular weight amino group-containing compound, and the haze of the obtained polyester molded article is good.
These polyamide compounds, low molecular weight amino group-containing compounds, hydroxyl group-containing compounds and other aldehyde reducing agents may be used alone or in admixture at an appropriate ratio.
The aldehyde reducing agent is, for example, used in an amount of 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the polyester composition of the present invention. Can do.

  The polyester composition of the present invention can be obtained by using a polyester having the characteristics specified in the claims of the present invention and a recovered product and mixing them by a conventionally known method. For example, a method of dry blending the polyester and the recovered product with a tumbler, V-type blender, Henschel mixer, etc., and a method of melt-mixing the dry blended mixture once or more with a single screw extruder, twin screw extruder, kneader, etc. Is mentioned. It is also possible to mix only the virgin polyester by the above method and further mix the recovered product.

  The polyester composition of the present invention is formed by using a generally used melt molding method to form a sheet-like material, a biaxially stretched film, a hollow molded body, a tray or other packaging material, or by another melt extrusion method. A coated coating can be formed on the substrate. The polyester composition of the present invention can be preferably used as a hollow molded product, a tray, a packaging material such as a biaxially stretched film, a metal can coating film, a fiber containing a monofilament, and the like. Moreover, the polyester composition of this invention can be used also as 1 component layers, such as a multilayer molded object and a multilayer film. It can also be used as a base material on which an oxygen barrier film such as carbon or silica is deposited.

  The method for producing a polyester molded body from the polyester composition of the present invention will be briefly described below by taking a polyester composition containing, as a main component, a polyester having ethylene terephthalate as a main repeating unit as an example, but is limited thereto. It is not a thing. The polyester composition of the present invention is formed by using a generally used melt molding method after the moisture content is reduced to about 100 ppm or less, preferably 50 ppm or less by heat drying under reduced pressure or heat drying under an inert gas. A molded body to be a sheet, a container, or other packaging material can be molded. As conditions for the molding production, the molten resin temperature is 260 to 295 ° C., preferably 262 to 290 ° C., more preferably 265 to 265 ° C. by heating a barrel, a die, a hot runner, etc. of an injection molding machine or an extrusion molding machine. It is important to set the temperature within the range of 285 ° C. Here, the molten resin temperature refers to a temperature obtained by immediately measuring, for example, a thermocouple thermometer with a resin injected or extruded from a nozzle tip or a die outlet of an injection molding machine or the like.

  In addition, the melt residence time in the molding machine can be set by arbitrarily selecting the shape of the extruder screw, L / D, etc. and the amount of extrusion in the case of extrusion molding, and in the case of injection molding, the injection molding machine The cycle time, the metering stroke (screw back amount) and the like are arbitrarily set, and the time is set in the range of 10 to 500 seconds, preferably 20 to 300 seconds, and more preferably 30 to 200 seconds. Here, the melt residence time is a residence time in a state where the resin is melted in the molding machine. Specifically, the melt residence time is a time during which the resin is melted and held in a cylinder in the molding machine and in a hot runner or a die. That is.

In the case of injection molding, if the melt residence time is t, t is given by the following formula (5).
t = W × S / P (5)
Here, W: Weight of molten resin (g) in a cylinder and hot runner of an injection molding machine, etc.
S: Molding cycle time (seconds)
P: Molded product weight (g)

  In the present invention, by controlling the molten resin temperature in the range of 260 to 295 ° C. and setting the melt residence time in the range of 10 to 500 seconds, the polyester composition of the present invention contains aldehyde such as acetaldehyde. Small amount, excellent flavor retention, excellent transparency, and no transparent spots (for example, whitened flow pattern or partially whitened or wrinkled product) Furthermore, a molded body such as a preform for a hollow molded body having no problem in the shape of the plug portion after crystallization can be obtained.

  When the temperature of the molten resin is less than 260 ° C., the torque load of an injection molding machine or the like is large and molding becomes difficult, the obtained preform becomes extremely poor in transparency, and the thickness of the sheet-like material varies. growing. Moreover, when the temperature exceeds 295 ° C., the thermal decomposition becomes intense and the content of aldehyde such as acetaldehyde becomes high, which is a problem. When the melt residence time is less than 10 seconds, the transparency of the preform is deteriorated due to insufficient melting, and when it exceeds 500 seconds, the transparency of the preform is very good, but aldehydes such as acetaldehyde. As a result, the molding cycle becomes longer and the productivity of the preform is lowered.

  Here, the polyester composition containing ethylene terephthalate as the main repeating unit and the polyester composition containing the recovered product as the main component has been described. However, the temperature of the molten resin when the preform is produced from the polyester composition of the present invention is the constituent polyester. It is necessary to control the set temperature of the barrel of an injection molding machine or the like or a hot runner so that the melting point is higher by 10 to 45 ° C., preferably 10 ° C. to 40 ° C., more preferably 30 ° C.

  Here, the polyester molded body refers to a polyester molded body such as a sheet-like material or a cup-like material used as it is and the following polyester preform. A polyester preform is a non-stretched sheet obtained by melt extrusion molding polyester, a preform obtained by compression molding a melt mass obtained by melt extrusion molding, or obtained by injection molding. It is a preform that can be used. Further, it is a molded body that is melt-extruded and extruded into a pipe shape (so-called direct blow molded body), and then a cylindrical molded body that is further molded into a container, a cup-shaped molded body that is obtained by injection molding, Also included are molded products that are commercialized as containers by laminating paper and non-woven fabrics.

  Moreover, it is possible to improve mechanical strength by extending | stretching the sheet-like material which consists of a polyester composition of this invention at least to a uniaxial direction. The stretched film composed of the polyester composition of the present invention is a sheet-like material obtained by injection molding or extrusion molding, and can be any one of uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching that are usually used for PET stretching. It is molded using a stretching method. It can also be formed into a cup shape or a tray shape by pressure forming or vacuum forming.

Below, the specific manufacturing method about the extending | stretching molded object in the case of PET is demonstrated easily.
In producing a stretched film, the stretching temperature is usually 80 to 130 ° C. Stretching may be uniaxial or biaxial, but biaxial stretching is preferred from the viewpoint of film physical properties. In the case of uniaxial stretching, the stretching ratio is usually 1.1 to 10 times, preferably 1.5 to 8 times. In the case of biaxial stretching, the longitudinal and transverse directions are usually 1.1 to 8 times, respectively. Preferably, it may be performed in a range of 1.5 to 5 times. The vertical / horizontal magnification is usually 0.5 to 2, preferably 0.7 to 1.3. The obtained stretched film can be further heat-set to improve heat resistance and mechanical strength. The heat setting is usually performed under tension at 120 to 240 ° C., preferably 150 to 230 ° C., usually for several seconds to several hours, preferably several tens of seconds to several minutes.

  In producing a stretched hollow molded body, a foam molded from the polyester composition of the present invention is stretch blow molded, and an apparatus conventionally used in blow molding of PET can be used. Specifically, for example, once a preform is formed by injection molding or extrusion molding, the plug part and the bottom part are processed as it is, and then reheated, and then biaxial stretch blow molding such as hot parison method or cold parison method The law applies. The molding temperature in this case, specifically, the temperature of each part of the cylinder of the molding machine and the nozzle is usually in the range of 260 to 300 ° C. The stretching temperature is usually 70 to 120 ° C., preferably 90 to 110 ° C., and the stretching ratio is usually 1.5 to 3.5 times in the longitudinal direction and 2 to 5 times in the circumferential direction. The obtained hollow molded body can be used as it is, but in particular in the case of beverages that require hot filling, such as fruit juice beverages and oolong teas, in general, heat-setting treatment is performed in a blow mold, Used to impart sex. The heat setting is usually performed at 100 to 200 ° C., preferably 120 to 180 ° C. for several seconds to several hours, preferably several seconds to several minutes, under tension by compressed air or the like.

  In addition, in order to impart heat resistance to the plug part, the plug part of the preform obtained by injection molding or extrusion molding is crystallized in a far-infrared or near-infrared heater installation oven, or after the bottle is formed, The stopper is crystallized with the heater.

Moreover, the manufacturing method of the polyester preform of this invention is applicable also to manufacture of the preform used for manufacture of the heat resistant bottle by the two-stage blow molding method provided with a primary blow molding process and a secondary blow molding process. be able to.
In the case of the two-stage blow molding method of PET, a preform obtained by crystallizing the plug portion as described above in the primary blow molding step is 1.0 to 1.0 to the final product volume at the same stretching temperature as described above. The biaxially stretched blow molding is performed about twice, and then the obtained primary molded body is heated at about 100 to 250 ° C. and then subjected to secondary blowing in a mold of about 80 to 200 ° C. in the secondary blow molding step.

  The polyester composition of the present invention can also be used for the production of a stretched hollow molded body by a so-called compression molding method in which a preform obtained by compression molding a melt mass cut after melt extrusion is stretch-blown. Can do.

Another use of the polyester composition of the present invention is a film laminated on one or both sides of a laminated metal plate. Examples of the metal plate used include tinplate, tin-free steel, and aluminum.
As a laminating method, a conventionally known method can be applied, and it is not particularly limited. However, it is preferable to carry out by a thermal laminating method that can achieve organic solvent-free and can avoid adverse effects on the taste and odor of food products due to the residual solvent. In particular, the thermal laminating method by energization processing of a metal plate is particularly recommended. In the case of double-sided lamination, they may be laminated simultaneously or sequentially.
Needless to say, a film can be laminated to a metal plate using an adhesive.
Moreover, a metal container is obtained by shape | molding using the said laminated metal plate. The method for forming the metal container is not particularly limited. Further, the shape of the metal container is not particularly limited, but is preferably applied to a so-called two-piece can produced by a molding process such as drawing, drawing and ironing, and stretch draw molding. The present invention can also be applied to a so-called three-piece can in which a top cover suitable for filling a food product such as a coffee drink is wrapped to fill the contents.

  In the polyester composition of the present invention, known ultraviolet absorbers, antioxidants, oxygen scavengers, lubricants added from the outside, lubricants precipitated internally during the reaction, mold release agents, nucleating agents, stability Various additives such as an agent, an antistatic agent, a bluing agent, a dye, and a pigment, and a polyamide resin from metaxylylenediamine and adipic acid may be added to improve oxygen permeability.

  In addition, when the polyester composition of the present invention is used for a film, in order to improve handling properties such as slipping property, winding property, and blocking resistance, calcium carbonate, magnesium carbonate, barium carbonate, sulfuric acid are included in the polyester. Inorganic particles such as calcium, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, organic salt particles such as calcium oxalate, calcium, barium, zinc, manganese, magnesium, terephthalate, divinylbenzene, styrene, acrylic acid, Inactive particles such as crosslinked polymer particles such as methacrylic acid, acrylic acid, or a vinyl monomer of methacrylic acid, alone or as a copolymer can be contained.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
The main characteristic value measurement methods will be described below.
(1) Intrinsic viscosity of polyester (IV)
It calculated | required from the solution viscosity at 30 degreeC in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent. The IV of the polyester composition was a weighted average value calculated from the IV of the constituent polyester.

(2) Polyethylene glycol content of polyester (hereinafter referred to as [DEG content])
Decomposition with methanol, the amount of DEG was quantified by gas chromatography, and expressed as a ratio (mol%) to the total glycol components.

(3) Polyester cyclic trimer content (hereinafter referred to as “CT content”)
300 mg of the frozen and ground sample is dissolved in 3 ml of a hexafluoroisopropanol / chloroform mixed solution (volume ratio = 2/3), and further diluted with 30 ml of chloroform. To this is added 15 ml of methanol to precipitate the polymer, followed by filtration. The filtrate was evaporated to dryness, brought to a constant volume with 10 ml of dimethylformamide, and the cyclic trimer was quantified by high performance liquid chromatography.

(4) Acetaldehyde content of polyester (hereinafter referred to as “AA content”)
Sample / distilled water = 1 g / 2 cc of glass ampoule substituted with nitrogen was sealed and subjected to extraction treatment at 160 ° C for 2 hours. After cooling, acetaldehyde in the extract was measured by high-sensitivity gas chromatography. The concentration was expressed in ppm. In the case of a preform, a sample was taken from the mouth.

(5) Increasing amount of cyclic trimer at the time of melting polyester (△ CT amount)
After cutting out a small piece of about 1 to 3 mm in size from the mouth of the preform formed in (11) and then drying it, 3 g of this polyester sample was placed in a glass test tube and heated at 290 ° C. under a nitrogen atmosphere. Immerse in an oil bath for 60 minutes to melt. The amount of increase in cyclic trimer at the time of melting is determined by the following equation.
Increase in cyclic trimer during melting (wt%) =
Cyclic trimer content after melting (wt%)-cyclic trimer content of preform before melting (wt%)

(6) Measurement of number average molecular weight (Mn), Z average molecular weight (Mz) and dispersion ratio
Average molecular weight and molecular weight fraction were determined by GPC method.
(Preparation of sample) 1 mg of a sample was dissolved in 0.2 ml of chloroform / hexafluoroisopropanol = 3/2 (vol%), and then diluted with 3.8 ml of chloroform to prepare a sample solution.
(Eluent) Chloroform / hexafluoroisopropanol = 98/2 (vol%)
(Apparatus) TOSOH HLC-8220GPC manufactured by Tosoh Corporation was used.
(Column) TSKgel SuperHM-H × 2 + manufactured by Tosoh Corporation
TSKgel SuperH2000
(Standard polystyrene) TSK standard polystyrene manufactured by Tosoh Corporation was used.
(Measurement conditions) Measurement temperature 40 ° C., flow rate 0.6 ml / min (detector) UV detector 254 nm
(Molecular weight conversion) Calculation was performed in terms of standard styrene.
(Integration range) The peak start was set to 700 with standard polystyrene, and the peak end was set to 700 with standard polystyrene.
The dispersion ratio was determined from the following.
Dispersion ratio = Mz / Mn
In the case of a preform molded by the above method, a sample was taken from the mouth.

(7) Crystallization temperature (Tc1) when the molded body is heated and crystallization temperature (Tc2) when the temperature is lowered
Measured with a differential thermal analyzer (DSC), RDC-220, manufactured by Seiko Electronics Industry Co., Ltd. A 10 mg sample from the center of a 2 mm thick plate of the molded plate of (10) below is used. In the case of a preform, a sample was taken from the trunk.
The temperature was raised at a rate of temperature rise of 20 ° C./minute and held at 290 ° C. for 3 minutes, then the temperature was lowered from 290 ° C. to 240 ° C. at 10 ° C./minute, and further from 240 ° C. to 130 ° C. at 7 ° C./minute. The temperature dropped. The peak temperature of the crystallization peak observed at the time of temperature rise is defined as the crystallization temperature (Tc1) at the time of temperature increase, and the peak temperature of the crystallization peak observed at the time of temperature decrease is defined as the crystallization temperature (Tc2).

(8) Density of polyester chip It was measured at 30 ° C. with a density gradient tube of calcium nitrate / water solution.

(9) Haze (Fraction%)
A sample was cut from the molded product (thickness 5 mm) of the following (10), and measured with a Nippon Denshoku Co., Ltd. haze meter, model NDH2000.

(10) Molding of Stepped Molding Plate The polyester dried under reduced pressure at 140 ° C. for about 16 hours using a vacuum dryer DP61 type manufactured by Yamato Kagaku for about 16 hours using an injection molding machine M-150C-DM type injection molding machine manufactured by Meiki Seisakusho. 2 having a gate part (G) as shown in FIG. 2 (thickness of A part = 2 mm, thickness of B part = 3 mm, thickness of C part = 4 mm, thickness of D part = 5 mm, E part of A stepped molded plate having a thickness of 10 mm and a thickness of F portion of 11 mm was injection molded.

In order to prevent moisture absorption during molding, the inside of the molding material hopper was purged with a dry inert gas (nitrogen gas). The plasticizing conditions of the M-150C-DM injection molding machine are as follows: feed screw rotation speed = 70%, screw rotation speed = 120 rpm, back pressure 0.5 MPa, cylinder temperature 45 ° C., 250 ° C. from the bottom of the hopper in order, nozzle Including 280 ° C. or 290 ° C. The injection conditions are 20% for injection speed and holding pressure, and the injection pressure and holding pressure are adjusted so that the weight of the molded product is 146 ± 0.2g. In this case, the holding pressure is 0.5MPa lower than the injection pressure. It was adjusted.
The upper limit of the injection time and pressure holding time is set to 10 seconds and 7 seconds, respectively, and the cooling time is set to 50 seconds. The total cycle time including the time for taking out the molded product is about 75 seconds.

Although the temperature of the mold is always controlled by introducing cooling water having a water temperature of 10 ° C., the mold surface temperature at the time of stable molding is around 22 ° C.
The test plate for evaluating the molded product characteristics was arbitrarily selected from the 11th to 18th shots of the stable molded product after the molding material was introduced and the resin was replaced. The molding temperature refers to the set temperature of the barrel including the nozzle, and a molding plate having a molding temperature of 280 ° C. was used to measure the haze of the molding plate.
A 2 mm-thick plate (part A in FIG. 1) measures the crystallization temperature (Tc1) at the time of temperature rise and a crystallization temperature (Tc2) at the time of the temperature drop, and the 5 mm-thick plate (part D in FIG. 1) has a haze (degree) %) Used for measurement.

(11) Molding of hollow molded body 1) Molding of preform In order to prevent moisture absorption of the chip during molding using a polyester chip that has been dried in advance using a vacuum dryer DP63 manufactured by Yamato Scientific, Was purged with a dry inert gas (nitrogen gas).
The plasticizing conditions of the M-150C-DM injection molding machine manufactured by Meiki Seisakusho include feed screw rotation speed = 70%, screw rotation speed = 120 rpm, back pressure 0.5 MPa, weighing position 50 mm, and cylinder temperature in order from directly under the hopper. The temperature was set to 45 ° C., 250 ° C., and thereafter 280 ° C. including the nozzle. The injection conditions were such that the injection speed and holding pressure were 10%, and the injection pressure and holding pressure were adjusted so that the weight of the molded product was 58.6 ± 0.2 g. Adjusted to 5 MPa lower. The cooling time is set to 20 seconds, and the total cycle time including the molded product take-out time is approximately 42 seconds. The preform has an outer diameter of 29.4 mm, a length of 145.5 mm, and a wall thickness of about 3.7 mm.

  The mold is always controlled by introducing cooling water having a water temperature of 18 ° C., but the mold surface temperature at the time of molding stability is around 29 ° C. The preform for property evaluation was arbitrarily selected from stable molded products 20 to 50 shots after the start of molding after introducing the molding material and replacing the resin. Take a sample from the mouth of the preform, measure the intrinsic viscosity, acetaldehyde content (AA content), cyclic trimer content (CT content), number average molecular weight (Mn), Z average molecular weight (Mz) and dispersion Used for ratio measurement.

2) Molding of stretched hollow molded body (bottle) The plug portion of the preform was heated and crystallized with a home-made plug portion crystallization apparatus. Next, this preform was biaxially stretched and blown at a magnification of about 2.5 times in the longitudinal direction and about 3.8 times in the circumferential direction on a LB-01E molding machine manufactured by CORPOPLAST, and subsequently set at about 145 ° C. It was heat-set in the mold for 7 seconds to mold a 1500 cc container (trunk thickness 0.45 mm). The stretching temperature was controlled at 100 ° C., and any one of 10 to 30 shots of a stable molded product from the start of molding was arbitrarily selected.

(12) Appearance of Hollow Molded Body Twenty hollow molded bodies from the tenth molding start of (11) were visually observed and evaluated as follows.
◎: Transparent and no appearance problem △: There is a little whitened flow pattern or whitened product in the hollow molded body ×: White flowed pattern or whitened product in the hollow molded body

(13) Shape and dimension of the plug part of the preform for the hollow molded body The shape and dimension of the plug part crystallized in (11) were visually observed and evaluated as follows.
A: Extremely stable dimensional accuracy was obtained.
○: Stable dimensional accuracy was obtained.
X: Insufficient crystallization, poor shape, or excessive crystallization, poor dimensionality.

(Polyester 1)
High purity terephthalic acid and ethyl glycol are continuously supplied to the first esterification reactor containing the reactants in advance, and the average residence time is 3 hours at about 250 ° C. and 0.5 kg / cm ² G with stirring. Reaction was performed. In addition, crystalline germanium dioxide was dissolved in water by heating, ethylene glycol was added thereto, and the heat-treated catalyst solution, and the ethylene glycol solution of phosphoric acid and ethylene glycol were continuously supplied separately to the first esterification reactor. This reaction product was sent to the second esterification reactor, and the reaction was carried out with stirring at about 260 ° C. and 0.05 kg / cm ² G to a predetermined reactivity. The esterification reaction product is continuously sent to the first polycondensation reactor and stirred for about 1 hour at about 265 ° C. and 25 torr, then stirred for about 2 hours at about 265 ° C. and 3 torr for 1 hour. Further, polycondensation was performed at about 275 ° C. and 0.5 to 1 torr with stirring in the third polycondensation reactor. The intrinsic viscosity (IV) of the obtained PET resin was 0.53.

  In addition, as cooling water at the time of chip formation, sodium content is 0.1 ppm, calcium content is about 0.1 ppm, magnesium content is about 0.06 ppm, silicon content is about 0.7 ppm, and COD is 0. .3 mg / l of ion exchange water was used. The sodium content, calcium content, magnesium content and silicon content in the chip cooling water were measured with a 1G1 glass filter manufactured by Iwaki Glass Co., Ltd., and the filtrate was measured using an inductively coupled plasma emission spectrometer manufactured by Shimadzu Corporation. did. COD was measured according to the method of JIS-K0101.

  After fine removal of this resin, it was subsequently crystallized at about 155 ° C. in a nitrogen atmosphere, further preheated to about 200 ° C. in a nitrogen atmosphere, and then sent to a continuous solid-phase polymerization reactor for solid phase polymerization at about 207 ° C. in a nitrogen atmosphere. . After the solid-phase polymerization, fines were removed by continuous treatment in a sieving step and a fine removal step.

The PET obtained had an intrinsic viscosity of 0.70 deciliter / gram, an acetaldehyde (AA) content of 3.2 ppm, a cyclic trimer content of 0.32 wt%, and a density of 1.399 g / cm ³ . .
The properties of the obtained PET are shown in Table-1.

(Polyester 2, 3)
Polyesters 2 and 3 were obtained by reacting in the same manner as polyester 1 except that the amount of polycondensation catalyst added and the solid phase polymerization time were changed.
The properties of the obtained PET are shown in Table-1.

(Polyester 4, 5)
The above polyester 1 or 2 is continuously charged from the supply port (1) at the top of the treatment tank to the following water treatment tank controlled at a treatment water temperature of 95 ° C. at a rate of 50 kg / hour for water treatment. A PET chip was continuously extracted from the lower discharge port (3) with treated water at a rate of 50 kg / hour. In the introduced water collected before the ion exchange water inlet (9) of the water treatment apparatus, the particle content of 1 to 25 μm in particle diameter is about 1500 particles / 10 ml, the sodium content is 0.03 ppm, and the magnesium content is 0.1. 07 ppm, calcium content 0.06 ppm, silicon content 0.12 ppm, and the number of particles of 1-40 μm recycled water after treatment in the filtration device (5) and adsorption tower (8) is about 10,000. Pieces / 10 ml. After the water treatment, fines and the like were removed in the same manner as in Example 1.

For the water treatment of the PET resin chip, using the apparatus shown in FIG. 3, the raw material chip supply port (1) at the upper part of the treatment tank, the overflow discharge port (2) located at the upper limit level of the treatment water of the treatment tank, the lower part of the treatment tank A discharge port (3) of a mixture of aromatic polyester chips and treated water, treated water discharged from the overflow outlet, treated water discharged from the treatment tank, and discharged from the discharge section at the bottom of the treatment tank Pipe (6) where the treated water passing through the draining device (4) is sent again to the water treatment tank via the fine powder removing device (5) whose filter medium is a paper 30 μm continuous filter, removing these fine powders Of treated water with an internal capacity of about 50 m ³ , equipped with an inlet (7) for treated water, an adsorption tower (8) for adsorbing acetaldehyde in treated water after fine powder removal, and an inlet (9) for new ion-exchanged water Use treatment tank It was.

  The properties of the obtained PET are the same as those of the polyester 1 or 2 described in Table 1, except that the cyclic trimer increase amount (ΔCT amount) upon melting is 0.13% by weight.

(Recovered product of polyester molded product 1)
A pre-molded product obtained by injection-molding a polyester composition obtained by blending the above-mentioned polyester 1 and polyester 2 pellets in a ratio of 7: 3 by the method (11) at a molten resin temperature of 280 ° C. And was used as a recovered product in the following tests. The intrinsic viscosity is 0.71 deciliter / gram, the acetaldehyde (AA) content is 10.2 ppm, the cyclic trimer content is 0.34% by weight, ΔCT is 0.43% by weight, and the molecular weight distribution dispersion ratio Mz / Mn was 4.06.

(Recovered product of polyester molded product 2)
A pre-molded product obtained by injection-molding a polyester composition obtained by blending the above polyester 4 and polyester 5 pellets in a ratio of 7: 3 by the method (11) at a molten resin temperature of 280 ° C. And was used as a recovered product in the following tests. The intrinsic viscosity is 0.71 deciliter / gram, the acetaldehyde (AA) content is 8.3 ppm, the cyclic trimer content is 0.33% by weight, ΔCT is 0.13% by weight, and the molecular weight distribution dispersion ratio Mz / Mn was 4.35.

(Recovered product of polyester molded product 3)
A preformed product obtained by injection molding of the above polyester 3 by the method (11) at a molten resin temperature of 280 ° C. was cut into small pieces with a pulverizer and used as a recovered product in the following tests. The intrinsic viscosity is 0.71 deciliter / gram, the acetaldehyde (AA) content is 16.3 ppm, the cyclic trimer content is 0.33% by weight, ΔCT is 0.43% by weight, and the molecular weight distribution dispersion ratio Mz / Mn was 3.62.

(Polyester molded product collection 4)
A polyester composition obtained by blending the above polyester 1 and polyester 2 pellets in a ratio of 7: 3 was injected by the method (11) under the conditions of a molten resin temperature of 300 ° C. and a melt residence time of about 600 seconds. The preformed body obtained by molding was cut into pieces with a pulverizer and used as a recovered product in the following tests. The intrinsic viscosity is 0.64 deciliter / gram, the acetaldehyde (AA) content is 35.2 ppm, the cyclic trimer content is 0.43% by weight, ΔCT is 0.48% by weight, and the molecular weight distribution dispersion ratio Mz / Mn was 3.58.

Example 1
Molded plate obtained by molding the polyester composition obtained by blending the above polyester 1 and polyester 2 pellets in a ratio of 7: 3 with 5% by weight of the recovered product 1 at 280 ° C. by the method (10). And the evaluation by the preform and hollow molding container which were obtained by injection molding by the method of (11) was carried out. The results are shown in Table 2.

  The haze of the molded plate is 7.8%, which is a satisfactory value, the shape and dimensions of the preformed body plug after crystallization are satisfactory, and the AA content of the stretched hollow molded body is as low as 10.9 ppm, Also, there was no problem with the appearance of the hollow molded container.

(Example 2)
According to the composition shown in Table 2, the polyester composition of Example 2 was evaluated in the same manner as in Example 1. The results are shown in Table 2. All the evaluated characteristics were as good as in Example 1.

(Comparative Example 1)
The polyester compositions shown in Table 2 were evaluated in the same manner as in Example 1.
Obviously, the haze value of the molded plate is high, the shape after crystallization of the preformed body plug portion is poor and poor in dimensions, and the AA content and appearance of the hollow molded container are not so good as compared with the examples. It was. The results are shown in Table 2.

(Comparative Example 2)
As shown in Table 2, the polyester composition of Comparative Example 2 was evaluated.
Obviously, the haze value and AA content of the molded plate were high, and the shape of the preformed plug portion after crystallization was poor and poor in size when compared with the examples. The results are shown in Table 2.

  Since the flow characteristics are improved, the present invention is excellent in transparency and has little variation in transparency, the amount of aldehyde generated during molding and its variation is small, and an appropriate crystallization rate when formed into a molded body And a polyester composition that gives a molded article having excellent mechanical properties. In addition, the polyester composition of the present invention has improved flow characteristics, so there is less distortion during molding, and a molded body with an appropriate heat-resistant dimensional stability with an appropriate crystallization speed, especially a hollow molded product, can be efficiently obtained by high-speed molding Provided is a polyester molded body that can be produced well and has excellent long-term continuous moldability with less fouling of a mold. The polyester composition of the present invention can meet high quality requirements in the field of containers, sheets and the like.

Plan view of stepped plate Side view of stepped plate It is the schematic of the water treatment apparatus used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material chip supply port 2 Overflow discharge port 3 Drain port of polyester chip and treated water 4 Drainage device 5 Fine removal device 6 Pipe 7 Recycled water and / or ion exchange water introduction port 8 Adsorption tower 9 Ion exchange water introduction port

Claims (9)

  A polyester composition comprising at least two types of polyesters having substantially the same composition and different intrinsic viscosities, and a recovered product of a polyester molded product, the difference in intrinsic viscosities of the polyesters being 0 A polyester composition characterized in that it is in the range of 0.05 to 0.30 deciliter / gram, and the content of the recovered product of the polyester molded body in the polyester composition is 0.1 to 10% by weight.   A polyester molded product is obtained by melt-molding a polyester mixture containing at least two kinds of polyesters having substantially the same composition and a difference in intrinsic viscosity of 0.05 to 0.30 deciliter / gram as main components. The polyester composition according to claim 1, wherein the polyester composition of the recovered product is substantially the same as the composition of the polyester according to claim 1.   The polyester composition according to claim 1, wherein a dispersion ratio Mz / Mn of a molecular weight distribution of a recovered product of the polyester molded product is 3.80 or more.     The polyester composition according to any one of claims 1 to 3, wherein an aldehyde content of a recovered product of the polyester molded body is 20 ppm or less.     The polyester composition according to any one of claims 1 to 4, wherein the cyclic ester oligomer content of the recovered polyester molded product is 70% or less of the cyclic ester oligomer content of the melt polycondensed polyester.   The polyester according to any one of claims 1 to 5, wherein an increase amount of the cyclic ester oligomer when the recovered product of the polyester molded article is melted at a temperature of 290 ° C for 60 minutes is 0.40% by weight or less. Composition.    A polyester molded article obtained by molding the polyester composition according to claim 1.   The polyester molded body according to claim 7 is a hollow molded body preform, a sheet-shaped preform, or a stretched film or stretch blown hollow molded body obtained by stretching these preforms in at least one direction. A polyester molded body characterized by being selected.   The polyester molded article according to claim 7, wherein the polyester molded article is a coating obtained by melt-extruding a polyester composition on a substrate.

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